Self-commutated actuator

ABSTRACT

An integrated motor-transmission unit in which an output gear and a coaxial stationary gear coact with a driven eccentric ring gear that meshes therewith to provide for a direct drive of the output gear by driving the ring gear. A force vector is applied to the ring gear so as to move the ring gear such that the axis thereof travels in an orbital path about the output gear axis, and this movement of the ring gear is utilized to provide for rotation of the force vector. In the illustrated embodiment of the invention an electromagnet and switching circuit assembly provide for this movement of the force vector.

United States Patent [72] lnventor Kenneth W. Verge Farmington, Mich.[211 Appl. No. 795,804 [22] Filed Feb. 3, 1969 [45] Patented Jan. 26,1971 [73] Assignee The Bendix Corporation a corporation of DelawareContinuation-impart of application Ser. No. 523,111, Jan. 26, 1966, nowabandoned, Continuation-impart of application Ser. No. 667,459, Sept.13, 1967 [54] SELF-COMMUTATED ACTUATOR 9 Claims, 8 Drawing Figs. [52]US. Cl 310/82, 74/804; 310/83 [51] 1nt.Cl l-l02k 7/10 [50] FieldofSearch 310/82, 83. 84; 74/804 [56] References Cited UNITED STATESPATENTS 3,452,227 6/1969 Welch 310/82 1,471,606 10/1923 Holmdahl 74/804Primary ExaminerMilton O. Hirshfield Assistant Examiner-Mark O. BuddAttorneys-William F. Thorton and Flame, Hartz, Smith &

Thompson ABSTRACT: An integrated motor-transmission unit in which anoutput gear and a coaxial stationary gear coact with a driven eccentricring gear that meshes therewith to provide for a direct drive of theoutput gear by driving the ring gear. A force vector is applied to thering gear so as to move the ring gear such that the axis thereof travelsin an orbital path about the output gear axis, and this movement of thering gear is utilized to provide for rotation of the force vector. Inthe illustrated embodiment of the invention an electromagnet andswitching circuit assembly provide for this movement of the forcevector.

' PATENTED mas ml min 1 M2 INVENTOR w. VERGE ATTORNEY SELF-COMMUTATEDACTUATOR CROSS REFERENCE TO RELATED APPLICATIONS 1966. now abandonedand, Ser. No. 667.459 filed Septemben I3, 1967. assigned to the assigneeof this application.

BACKGROUND OF THE INVENTION The actuator of this invention is anintegrated motor-transmission unit which is driven by a rotating radialforce vector and in which a desired transmission ratio is an integralpart of the structure.

SUMMARY OF THE INVENTION The basic components of the actuator of thisinvention are described in detail in the aforementioned copendingapplication Ser. No. 667,459 as consisting essentially of an outputgear, a stationary gear mounted in a fixed position with respect to theoutput gear and in a coaxial relation therewith, and a ring gear whichis eccentric with respect to the output gear axis and has two sets ofteeth, one set meshing with the stationary gear and the other setmeshing with the output gear.

The ring gear is mounted for floating movement, namely, movement inwhich the axis of the gear moves so that the gear does not move about afixed center. The portions of the ring gear which mesh with thestationary and output gears enables the stationary gear to apply areaction force to the ring gear which in turn enables the ring gear toapply an output force to the output gear causing it to rotate.

The motor input is a force, hereinafter referred to as a force vectorsince it can be the resultant of several forces, applied to the ringgear at a position angularly spaced from the reaction and output forcesso as to cause the ring gear axis to move in an orbital path about theaxis of the output gear, with the ring gear experiencing epicyclicmovement relative to both the output and stationary gears. The ring gearaxis orbits in a small circle having a radius equal to the eccentricityof the ring gear relative to the output gear. Since the center of massof the ring gear must therefore be moved only in a small circle. thepolar moment of inertia of the ring gear is small compared to mostconventional 'motors. This reduces the force necessary to accelerate ordecelerate the moving portions of the motor. As a result, the motor ofthis invention can be operated with relatively small input forces, andis particularly adapted for controlled drives where changes in motoroutput yelocity must be frequent and rapid.

The motor input force vector extends perpendicular to the axis of thestationary and output gears and must be moved in a circular pathextending about that axis in order to keep the ring gear moving in itsorbital path. The aforementioned copending application disclosesapparatus which is external to the motor for moving the force vector inthis circular path. The present invention includes structure responsiveto movement of the ring gear for moving the force vector in its circularpath. Hence, the actuator of this invention is referred to herein asbeing self-commutated since it incorporates structure for keeping theforce vector moving. This structure consists of a plurality ofelectromagnets which are extended about the gear axis and a switchassembly which provides for sequential energization of theelectromagnets so as to effect the desired movement of the radiallyinwardly directed force vector. This switch assembly consists of aswitch ring mounted on the ring gear in a concentric relation therewithand fixed arcuate switch segments arranged in a circular formationconcentric with the output gear axis. The switch ring engages thesegments and moves relative thereto so as to effect the desiredcommutation Further objects, features and advantages of this inventionwill become apparent from a consideration of the following description,the appended claims, and the accompanying drawing in which:

FIG. 1 is a transverse sectional view of the actuator of this invention;

FIGS. 2 and 3 are sectional views of the actuator of this invention asseen from the lines 2-2 and 3-3, respectively, in FIG. 1;

FIGS. 4, 5, 6 and 7 are diagrammatic illustrations of the switchassembly of this invention with the ring gear in progressively movedpositions; and

FIG. 8 is a diagrammatic view of a portion of the circuitry in theactuator of this invention.

With reference to the drawing, the actuator of this invention indicatedgenerally at 10, is illustrated in FIG. 1, as including a housing 12 onwhich a stationary gear 14, having external teeth 16, is fixedlymounted. The axis of the stationary gear 14 is shown at 18 and an outputgear 20 having having external teeth 22 is mounted on bearings 24 forrotation about the axis 18. A floating ring gear 26, formed of amagnetically permeable material, such as iron or steel, so that it canfunction as an armature, is positioned so that its axis 28 is eccentricwith respect to the axis 18 by a distance indicated at e in FIG. 2.

The ring gear 26 has a first set of internal teeth 30 which mesh withthe stationary gear teeth 16 and a second set of internal teeth 32 whichmesh with the output gear teeth 22. There are more teeth 30 than thereare teeth 16 and there are more teeth 32 than there are teeth 22. As aresult, and as explained in detail in the aforementioned copendingapplication Ser. No. 667,459 when a force vector, indicateddiagrammatically at F in FIGS. 4, 5, 6 and 7 is applied to the ring gear26 at a point angularly spaced from the points on the ring gear 26 whichmesh with the stationary gear 14 and the output gear 20, the ring gear26 is moved in an orbital path having the radius *e" so as to producerotation of the output gear 20 about the axis 18.

In the actuator 10, the force vector F is generated by electromagnetsindicated generally at 34, 35, 36 and 37, each of which includes a core,indicated at 40, 41, 42 and 43, respectively, and a coil assembly 46,47, 48 and 49, respectively. The electromagnets 34, 35, 36 and 37 aremounted on the housing 12 so that they extend in a circular path aboutthe axis 18.

Referring now to FIGS. 47, the provision for generating force vectorscausing counterclockwise rotation of the output gear 20 is illustrated.Such rotation is accomplished by sequentially energizing the coilassemblies 46-49 so as to provide a force vector F which rotates in acounterclockwise direction. A switch assembly, indicated generally at52, is provided which includes a switch ring 54 mounted on the ring gear26 in a concentric relation therewith, as shown in FIG. 1, the ring 54being of continuous circular shape. The assembly 52 also includes acircular switch segment unit 58 which is concentric with the axis 18 andengages the switch ring 54 in a manner hereinafter described. Thesegment unit 58 includes four arcuate segments 62, 63, 64 and 65, shownin FIGS. 4, 5, 6 and 7.

As shown in FIGS. 1 and 4, the ring 54 is eccentric with respect to thesegment unit 58 so that the ring 54 will engage the segment unit 58 atonly one or two points on the periphery thereof in each moved positionof the ring gear 26. As a result, during movement of the ring gear 26,the electromagnet coil assemblies 4649 will be sequentially energized ina manner to produce the desired location and movement of the forcevector F.

In FIGS. 1, 2 and 3, the ring gear 26 is in a downwardly moved positionin which it engages the stationary gear 14 and the output gear 20 atwhat is referred to herein for ease of understanding as the twelveoclock position. As will more clearly appear hereinafter, since thereare four electromagnets 3437 in the illustrated embodiment ofthe'invention, the ring gear 26 will move in 45 increments. Assume,therefore, that the ring gear 26 is in the twelve oclock position shownin FIG. 4. In this position of the ring gear, the switch ring 54 willengage the segment unit 58 in the position illustrated in FIG. 4,namely, a position in which the ring 54 engages only the segments 63 and64.

As shown in FIGS. 4, 5, 6 and 7, one end of each of the coil assemblies46-49 is connected to a conductor 74. The opposite end of the coil 46 isconnected to the segment 62, the opposite end of the coil 47 isconnected to the segment 63, the opposite end of the coil 48 issimilarly connected to the segment 64, and the opposite end of the coil49 is connected to the segment 65. As a result, with the switch ring 54positioned as shown in FIG. 4, and with the ring 54 connected by a lead78 to one terminal of a suitable current source, such as a battery (notshown), and the conductor 74 connected to the other terminal, currentwill flow through the coils 47 and 48 so that magnetic forces, indicatedat A and B, will be generated by the electromagnets 35 and 36. Theresulting force vector will thus be in the direction illustrated by thearrow F shown in FIG. 4.

The application of the force vector F shown in FIG. 4 to the ring gear26, which is now in a position in which it engages the stationary gear14 and the output gear 20 at the twelve oclock position, will be to movethe ring gear 26 counterclockwise through an angle of 45 to the positionillustrated in FIG. 5. In this position of the switch ring 54, itengages only the segment 63, so that only the electromagnet 35 isenergized This results in the generation of the single magnetic forceindicated by the arrow B, so that the resulting force vector will belocated as shown by the arrow F in FIG. 5.

Application of the force vector F shown in FIG. to the ring gear 26,will cause counterclockwise rotation of the ring gear 26 to the nineo'clock position in which the switch ring 54 will be positioned as shownin FIG. 6. As shown in FIG. 6, the ring 54 engages the segments 62 and63. This results in the generation of magnetic forces by theelectromagnets 34 and 35 indicated by the arrows B and C in FIG. 6. Theresulting force vector F is, as shown in FIG. 6, moved 45 degrees fromthe position shown in FIG. 5.

Application of the force vector F shown in FIG. 6 to the ring gear 26causes counterclockwise rotation of the ring gear 26 to the positionshown in FIG. 7 in which the switch ring 54 engages only the segment 62.As a result, only the electromagnet 34 is energized resulting in onlythe magnetic force indicated by the arrow C so as to locate the forcevector F at the position shown. The force vector F shown in FIG. 7 willin turn cause an additional counterclockwise rotation of the ring gear26 through an angle of 45. Subsequently, therefore, the switch ring 54is moved to positions in whichelectromagnets 34 and 37 are energized,then to a position in which only electromagnet 37 is energized then to aposition in which electromagnets 36 and 37 are energized, then to aposition in which only electromagnet 36 is energized, finally to returnto the position shown in FIG. 4. At such time the force vector F hasmade one complete revolution in a counterclockwise direction causingrotation of the output gear through a small angle determined by thedifference in the numbers of teeth on the ring, output and stationarygears.

The above cycle is continuously repeated to obtain continuouscounterclockwise rotation of the output gear 20.

As shown in FIG. 1 the switch assembly 52 is located at one side of thehousing 12. A similar switch assembly 53 consisting of a switch ring 56and a circular switch segment unit 60 is mounted on the opposite side ofthe housing 12. It should be noted from FIGS. 4-7 that each segment 6265is disposed on the clockwise side of the coil assembly 4649 to which itis connected. In the unit 60, segments identical to the segments 6265are employed but each of these segments is located on thecounterclockwise side of the coil assembly to which it is connected. Oneof the four segments 80 in the unit 60 is shown in FIG. 8, and furtherillustration and description of these segments is believed to beunnecessary because of their similarity to segments 6265.

Each of the coil assemblies 4649 is connected to the conductor 74 and apair of the segments in the units 58 and 60, as illustrateddiagrammatically in FIG. 8 for the coil 48. A pair of segments 64 and 80in the units 58 and 60, respectively, are

engageable with the switch rings 54 and 56, respectively,

which are in turn connected by leads 78 and 82, respectively, to thecurrent source. Switches 84 and 86 are interposed in the leads 78 and 82so that either the ring 54 or the ring 56 can be energized. As a result,when the conductor 74 and the ring 54 are connected to the currentsource, counterclockwise rotation of the output gear 20 is obtained andwhen the conductor 78 and the ring 56 are connected to the currentsource, clockwise rotation of the output gear 20 is obtained.

It can thus be seen from FIGS. 47 that the force vector F will berotated counterclockwise in 45 increments continuously so long as thereis current flow through the switch ring 54 and the conductor 74. Theapplication ofthe force vector F to the ring gear 26 results in thedesired movement of the ring gear 26 so that the axis 28 thereof orbitsin a counterclockwise direction about the output gear axis 18 with thering gear movement being utilized to rotate the force vector F. Thus, inthe motor 10 of this invention, the structure of the motor itselfprovides the desired movement of the radially directed force vector F sothat it rotates about the axis 18. Hence, the description of theactuator 10 as being self-commutated."

It is to be understood that the illustrated arrangements of theprincipal actuator components. namely. the stationary gaF'ii'imiitgihf'ga'r 2t], and the ring gear 26 is for illustrative purposesonly, since these components are subject to a large number ofarrangements within the scope of this invention, all as described in theaforementioned copending application Ser. No. 667,459. Also, therelative numbers of gear teeth employed on these components can bevaried to effect the direction of rotation of the output gear 20relative to the direction of rotation of the vector F. In all cases,these components are formed of metal or an equivalent rigid material andwhile these components have been illustrated as gears to accomplish adriving engagement therebetween, this driving engagement can beaccomplished without the use of teeth on the components. For example,frictional engagements of the components can be employed.

It will be understood that the self-commutated actuator which is hereindisclosed and described is presented for purposes of explanation andillustration and is not intended to indicate limits of the invention,the scope of which is defined by the following claims.

I claim:

1. An actuator comprising a stationary member, a rotatably mountedoutput member, said members being arranged in a coaxial relation, afloating ring ,member drivingly engaged with said stationary member anddrivingly engaged with said output member, said ring member having anaxis arranged eccentric with respect to the axis of said stationary andoutput members and being mounted for movement in an orbital path inwhich the axis of said ring member moves about said stationary andoutput member axis, first means for applying a resultant force to saidring member which is directed substantially perpendicularly relative tosaid stationary and output member axis, said force being applied to saidring member at one position thereon angularly spaced from the portionsof a said ring member which are drivingly engaged with said stationaryand output members so as to move said ring member in one direction insaid orbital path, and second means operable in response to saidmovement of said ring member to vary operation of said first means toprovide for rotated movement of said force to a second positionangularly spaced from said first position in a direction effective toprovide for continued movement of said ring member in said one directionin said orbital path, said second means being operable continuously toprovide for said rotated movement of said force to obtain said orbitalmovement of said ring member.

2. An actuator according to claim I wherein said stationary, output andring members are gears having teeth arranged so that the teeth on saidring gear engage the teeth on said stationary and output gears and saidforce is continuously applied to said ring gear at a position thereonangularly spaced from tionary and output gear teeth.

3. An actuator according to claim 1 wherein said means for applying aforce to said ring member includes electromagnet means arranged in acircular formation concentric with said stationary and output members,said ring member being formed of a magnetically permeable material andbeing disposed adjacent said electromagnet means for movement thereby.

4. An actuator according to claim 1 wherein said means for applying aforce to said ring member includes a plurality of electromagnetsarranged in a circular formation about said stationary and output memberaxis, circuit means including said electromagnets, said circuit meansincluding switch means operable in response to movement of said ringmember to provide for sequential energization of said electromagnets soas to effect said movement of said force.

5. An actuator according to claim 4 wherein said switch means includes aplurality of arcuate segments arranged in a circular formation and acontinuous circular ring eccentric with respect to said segments.

6. An actuator according to claim 5 wherein each of said segments isconnected to one of said clcctromagnets and is angularly offsettherefrom.

7. An actuator according to claim 4 wherein said switch means comprisesa pair of continuous switch rings mounted for movement with said ringmember and a pair' of substan tially circular axially spaced segmentunits corresponding to said switch rings, said segment units beingconcentric with each other and with said stationary and output memberaxis and eccentric with respect to said switch rings.

8. An actuator according to claim 7 wherein each segment unit includes aplurality of spaced arcuate segments arranged in a circularformation,each of said segments being connected to one of said electromagnets.

9. An actuator according to claim 8 wherein each of said switch rings ispositioned so that it can be moved to a position extending between theadjacent ends of adjacent segments in the corresponding segment unit.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION- Patent No.3,558,944 Dated January 26, 1971 Inventofl Kenneth w. Verue It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In Paragraph 73 of the face of the patent "Continuation-impart ofapp11'cat1'on Ser. No. 523,111 Jan. 26, 1966, now abandoned, Continuatiin-part of apphcation Ser. No.667,459, Sept. 13, 1967" shou1d be omiSigned and sealed this 13th day of July 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer WILLIAM E. SCHUYLER, JR.Commissioner of Patents

1. An actuator comprising a stationary member, a rotatably mountedoutput member, said members being arranged in a coaxial relation, afloating ring member drivingly engaged with said stationary member anddrivingly engaged with said output member, said ring member having anaxis arranged eccentric with respect to the axis of said stationary andoutput members and being mounted for movement in an orbital path inwhich the axis of said ring member moves about said stationary andoutput member axis, first means for applying a resultant force to saidring member which is directed substantially perpendicularly relative tosaid stationary and output member axis, said force being applied to saidring member at one position thereon angularly spaced from the portionsof said ring member which are drivingly engaged with said stationary andoutput members so as to move said ring member in one direction in saidorbital path, and second means operable in response to said movement ofsaid ring member to vary operation of said first means to provide forrotated movement of said force to a second position angularly spacedfrom said first position in a direction effective to provide forcontinued movement of said ring member in said one direction in saidorbital path, said second means being operable continuously to providefor said rotated movement of said force to obtain said orbital movementof said ring member.
 2. An actuator according to claim 1 wherein saidstationary, output and ring members are gears having teeth arranged sothat the teeth on said ring gear engage the teeth on said stationary andoutput gears and said force is continuously applied to said ring gear ata position thereon angularly spaced from the teeth on said ring gearwhich are engaged with said stationary and output gear teeth.
 3. Anactuator according to claim 1 wherein said means for applying a force tosaid ring member includes electromagnet means arranged in a circularformation concentric with said stationary and output members, said ringmember being formed of a magnetically permeable material and beingdisposed adjacent said electromagnet means for movement thereby.
 4. anactuator according to claim 1 wherein said means for applying a force tosaid ring member includes a plurality of electromagnets arranged in acircular formation about said stationary and output member axis, circuitmeans including said electromagnets, said circuit means including switchmeans operable in response to movement of said ring member to providefor sequential energization of said electromagnets so as to effect saidmovement of said force.
 5. An actuator according to claim 4 wherein saidswitch means includes a plurality of arcuate segments arranged in acircular formation and a continuous circular ring eccentric with respectto said segments.
 6. An actuator according to claim 5 wherein each ofsaid segments is connected to one of said electromagnets and isangularly offset therefrom.
 7. An actuator according to claim 4 whereinsaid switch means comprises a pair of continuous switch rings mountedfor movement with said ring member and a pair of substantially circularaxially spaced segment units corresponding to said switch rings, saidsegment units being conceNtric with each other and with said stationaryand output member axis and eccentric with respect to said switch rings.8. An actuator according to claim 7 wherein each segment unit includes aplurality of spaced arcuate segments arranged in a circular formation,each of said segments being connected to one of said electromagnets. 9.An actuator according to claim 8 wherein each of said switch rings ispositioned so that it can be moved to a position extending between theadjacent ends of adjacent segments in the corresponding segment unit.